Currently, the concerns about petroleum, coal and other fossil based energy consumption are growing due to the ever increasing environmental pollution caused by such consumption. Many countries have treated developing clean and renewable energy sources as an important energy strategy. Tidal-stream energy is an ocean based clean and renewable energy source. Such marine energy source is abundant, dense in coastal areas, predictable, stable and sustainable. Thus, the marine tidal-stream energy is superior to other renewable ocean energy sources in commercial value. Though the market competitiveness of the tidal-stream energy generation is still not competitive enough, from the technical aspect, the commercial competitiveness and perspective of the tidal-stream energy generation are certainly promising as long as certain technologies in tidal stream generators, tidal stream generator carrying device, and tidal-stream energy transmission and distribution are properly addressed at a high level. Currently, some solutions have been made in all these three technologies, but many shortcomings are still remaining. The existing tidal stream generator carrying device may be divided into the following categories based on the configuration format: float carried apparatus, pile carried apparatus, seabed carried apparatus, and semi-submerged float carried apparatus.